SU1080762A3 - Method and apparatus for electromagnetic logging - Google Patents

Abstract

1484200 Well logging SCHLUMBERGER Ltd 22 Aug 1974 [23 Aug 1973(2)] 36878/74 Heading G1N Micro-wave well-logging apparatus has a transmitter and two receiving antennas spaced along the log-tool whereby the dielectric constant of the earth formations can be determined from measurements of the phase difference and attenuation between the two received signals. The antennas may be cavity-backed-slots Figs. 6, 7 (not shown). In a basic arrangement Fig. 1, the transmitting antenna T is fed by oscillator 45, and the received signals from R1, R2 are heterodyned by beat oscillator 49 which is connected in a phaselocked-loop 50, 51 with the transmitter 45. The phase difference of the "intermediate" frequency signals is determined by phase detector 53, and the attenuation is determined by amplitude comparator 54. A more sophisticated PULSED SYSTEM is shown in Fig. 9, with two transmitting antennas T 1 ', T 2 ' alternately energized through switch 247 driven by a squarewave M from generator 260. In this system the received intermediatefrequency signals are fed to detectors 271, 272, which produce spiked pulses III, IV Fig.11, every time the signals I, II cross zero, in a positive direction, as shown. The phase displacement of the spikes is measured by a sub-system 270. The spikes are fed to gates 273..276 operated in synchronism with the antenna switch by pulses M, M from 260. These gates determine the duration of setting and resetting flip-flop 277 whose output pluses V, Fig. 11, are integrated at 278. Similarly a subsystem 280 is M, M switched to differential amplifier 289 to measure the average attenuation. From the dielectric constant information about the porosity, saturation or lithology of the strata may be estimated.

Description

1.1

The invention relates to an electromagnetic logging method and device for its implementation, namely, the study of earth formations using electromagnetic energy and, in particular, a method and device for determining the dielectric properties of subsurface formations by passing electromagnetic energy through them

Various methods are known for measuring the dielectric constant or dielectric constant of subsurface formations. As a result of the research conducted, it has been established that the dielectric constant of various materials of earth formations varies within wide limits (for example, 2.2 for oil; 7.5 for limestone and 8O for water) and that the measurement of dielectric properties can be used to evaluate these formations. For example, if the well logging method is used to determine the lithology and the degree of water saturation of a formation, the porosity of these formations can be determined by measuring the dielectric constant of a given material. Similarly, if lithogs and porosity are set as known data, then by measuring the dielectric constant of this formation, it is possible to determine the degree of saturation with water.

There is a known method for measuring dielectric constant or dielectric constant of subsurface technologies i.

The known devices for recording dielectric constant terrestrial formations in the spring wells do not provide reliable results for a number of reasons. Let us consider the common nature of the dielectric constant of a material with large losses, which msvkn can be represented as

6 The real part in this equality is the true value of the dielectric constant dd of the material without loss, t, e, the value obtained by measuring the wound gap of the current for a particular electric field in the material, not contributing to the loss. The imaginary part of this paBeHciv is the loss coefficient for this material, i.e. according to / 62J

loss due to conduction and reflection effects. Most of the known methods are based on measuring the magnitude of a subsurface formation. However, the materials of subsurface formations have significant conductivity and, therefore, have a significant loss coefficient C, the value of which often exceeds the value. As a result, obtaining accurate values of the value is greatly distorted by the presence of a significant loss coefficient.

The closest to this is an electromagnetic logging method, in which electromagnetic energy is excited in surrounding formations to form a secondary wave in them, which measures the speed of propagation of electromagnetic energy through this part of the surrounding formations, while the rate is an indicator of the parameters of earth formations 2.

The conductivity of the studied formation was established by indirect measurement of the skin layer thickness in the transverse direction of this formation, which is explained as follows. The magnetic intensity in Hg at a distance z f with large Z values from the transmitter is expressed as

"Z-Wo stHn, (

6 - represents the base of natural logarithms,

j - imaginary unit;

Hp is the intensity of the magnetic field at the transmitter)

8 - skin layer width, defined as

Th

r2j

UJ (U6 CO is the circular frequency (in radians) of the transmitter signal; jU is the magnetic permeability of the unspeakable formation, generally considered constant, 6 is the conductivity of the formation. A similar equation can be found for the dielectric field. Equation (1) indicates that Electro310 magnetic nwie is zag / huyushim, and its phase shifts as distance 2 increases, i.e. as pacnpoci wound electromagnetic energy in the formations under study. The magnitude of the phase shift is expressed by the term t and the degree of the last 1 field is expressed by a member - Z / S. Composite term x (, d +) hb Sig is the name of the constant distribution, the term 1/8 is called the damping constant, and the term is the constant phase. The damping constant and phase constant have the same values, so that the thickness of the skin layer can be determined either by measuring the attenuation value i or by measuring the phase. To calculate the attenuation, it is necessary to measure the magnitude of the electromagnetic energy at reception points located at a distance D from each other in a given formation. The measured amplitude values in the two receiving points, denoted as AJ and A, are used to calculate the thickness of the screen-layer in accordance with the following relationship: V dC. located reception points, which is indicated as calculated according to this ratio. R. By knowing S I, the conductivity of a formation can be calculated using the equality (2). This method is based on the assumption that the permanent phases and the droughts of electromagnetic energy are essentially equal. LL of such an assumption is true the following, where 5 - represents the soby1 dielectric constant of the material through which the electromagnetic wave propagates. The value of b / o, known as the loss angle tangent, represents the self-loss ratio of conduction currents to 624 displacement current. The loss tangent, a measure of the relative decrease in conductivity, contributes to the term loss coefficient 6. Thus, if the value of 6 is significant, and the operating frequency is relatively low, the constant propagation of the electromagnetic oscillation depends little on the true value of the dielectric constant. material This can be seen from equation (2), which does not reflect the dependence on the dielectric constant, and the resulting expression for a constant distribution i 1 (1 + j) The known method is implemented by a device containing a support column installed in the horizontal well, means of introducing electromagnetic energy into the surrounding formations spread on the support column, the transmitting antenna, the first and second receiving antennas installed in spatial communication with respect to the means of introducing electromagnetic energy and on a given p ssto SRI for otng leniyu to the surrounding formation, wherein the administration edektromagnitnY energy means connected to receive antennas, and an apparatus for measuring the velocity of propagation of electromagnetic energy through Danchi portion surrounding formations, and the measured velocity is indicative of the earth formation parameters. The purpose of the invention is to increase the measurement accuracy of the dielectric constant of the studied formations. This goal is achieved by the method of electrolytic magnetic logging, in which electrostatic energy is excited in surrounding formations to form secondary wave in them, including measurement of the velocity of propagation of electromagnetic energy through this part of the surrounding formations, when the velocity is with the parameter of the parameters of the earth formations , excite electromagnetic pope in the region of ultrahigh frequencies, namely in the range of 500 Mm - 2 GHz or, prefixally, at a frequency of 1.1 Gy + + 0.1 rtu. In a device for carrying out the method, comprising a support stitch, installed in a borehole, means for introducing electromagnetism of energy into surrounding formations located on the support strut, transmitting, first

and the second receiving antennas, installed in the proximate connection by oriochosony to the means of introducing electromagnetic energy and at a distance from the surrounding formation,

The means for introducing electromagnetic energy are connected to receiving antennas, and a device for measuring the speed of propagation of electromagnetic energy through this part of the surrounding formations, which is an indicator of the parameters of terrestrial formations, means for introducing electromagnetic energy contain a source of ultra-high frequencies

Fig. 1 shows schematically a block diagram of a device implementing cnoco6j in Figs. 2 and 3 in a simplified form, the nature of the propagation of an electromagnetic transverse band across a formation; FIG. 4 is the same; in the clean formation zone in FIG. 5, b is the “block diagram of the device of FIG. 1, in FIG. 6, a block diagram of the device shown in FIG. 5 is. comparing amsh1ud, fig, 7 is the block scheme of the computing module shown in figs 1 and 5; FIG. 8 is a side view of the pressing surface of the cushion shown in FIGS. 1 and 5; in fig 9. The section A-A in FIG. 8 on an enlarged scale,} in FIG. 10 is a block diagram for calculating the porosity representing a portion of the computational module shown in FIG. 5; Fig. 11 is a block diagram of a device which is the second version of the invention in Fig. 12, a pressure arm explaining the nature of the electromagnetic wave measured by the device shown in Fig. 11; on (jMir, 13 is a group of graphs that show the various waveforms that occur in the subsystem of the device shown in FIG. 11

First of all, it is necessary to consider a flat electromagnetic wave, spread out in a dielectric medium without loss. This wave propagates at a speed of

P1x: this is the first value, in this case it can be determined from the following

one

Consider two points located at a fixed distance from each other along the direction of propagation of the electromagnetic wave. For a given value of the angular frequency, i) the wave phase difference between these two points is determined by the following equation

.

where L is the distance between the data

two points

| i is the phase constant of the wave,

is equal to f g (O / V; By making the substitution from equation (3) one can see what can be obtained after determining the phase constant from the ratio / 2,

in the following way

R

(four)

(

The corresponding expression using the measured phase between two points has the form

R

(five)

Co LZfU

The given ratios are valid for a material without losses, however, the subsurface medium under investigation in general has significant conductivity. The constant propagation Y of a plane electromagnetic wave propagating in a medium without loss is a complex value of the form

()

where | U is the magnetic permeability,, is the diepeggric constant

this environment

If the material under study is generally a non-magnetic material, then (U can be considered as a wave pattern (6)

Jf CO t (and where 6 is the reducibility of the medium,

If the value of b / c is significantly greater than 1, then the propagation constant decreases; up to a value that is determined as shown in the description of the scope of the invention. For the case when 6 is zero or very vi. is small, the term loss angle can be neglected (6 / (o), as a result, it turns out that Jf P (.) l / (U, which is the case for equation (4) for the case when the material is considered lossless. If represents a significant amount, the loss tangent may be relatively small for very large values of LL in these cases, equality (4) is again approximately true. For example, if 6 / (about 0.2, then calculation of P1 to equation (4) gives an error of only O, 5% compared with the case when / s e. There are practical limits for choosing For example, for formations with significant conductivity, the use of the highest frequencies used in practice can lead to a significant increase in the loss tangent, which, if neglect of speech leads to an error in measuring the actual value of the dielectric constant. In this variant, the measurements made are automatically corrected taking into account the loss tangent LL of the continuous tim produced correcting the real and imaginary parts of the propagation constant Dost conveniently present as a 5 respectively and (, .In this case this value zapishets follows r- ((7), wherein 06 - the value of the conductive floating wave attenuation or loss. Attention should be paid to the fact that the constant propagation is used in the wave equation in the form of jjf, due to the real part of the constant distribution becomes the imaginary part of this exponent and vice versa. Having squared Eqs. (6) and (7) and their real parts equal to each other, the following p-res can be obtained. (8) Now, if we take the value from equation (4) and replace it with the corrected value (kp) which takes into account the losses, then we can get. (9) B28 From Eq. (8) it can be seen that the corresponding value of / 9 is coropredol ξc so f3. (o) in the embodiment of this retreaded value, the jp and volume values included in equation (10) are measured values, the value of B being determined by measuring the velocity or phase, and ot by measuring the attenuation. The required value of / 3 op is then determined using equation (1O). The compensated dielectric constant value calculates c from equation (9). Considering the above representation of the dielectric constant as a complex value (6 6H j e), it can be noted that the value of the dielectric constant determined by this method corresponds to . dielectric constant of the investigated material, which does not contribute losses. . The procedure for implementing the method is shown in FIG. 1, has a support post 1, made in the form of a supporting cylindrical element, installed in a borehole 2, means for introducing electromagnetic energy 3 into surrounding formations 4 located on the support post, the first and second receiving antennas 5, 6, distributed to the reference antennas), installed in spatial communication in relation to the means of introducing electromagnetic energy and at a definite distance (loading the formations from each other, while the means of introducing electromagitic energy are connected to aerial antennas and m for measuring the velocity of propagation of electrolytic energy 7 through this part of the wide formations, the measured speed being an indicator of the parameters of terrestrial formations, and the means of introducing electromagnetic energy contain a source of ultrahigh frequencies 8 "This device is intended to study the subsurface formations crossed by a borehole 2. Drilling hole is usually filled with washing fluid with a drilling fluid containing drilling mud containing finely divided solid particles forming spenziyu. The test device (probe) or registering device 9, its length essentially determines the relative depth of the device 9, the cable length is controlled by appropriate means located on the surface, for example using a drum or a winch (not shown). The recording device in FIG. 1 has a longitudinal cylindrical carrier 1, the inner part of which is made in the form of a liquid-impermeable housing in which the submersible electronic equipment is placed; Two arcs 11 and 12 are attached to the carrier D, contains a transmitting antenna T and receiving antennas 5 and 6 vertically spaced apart from each other. An additional cushion 14 is attached to P1, 12, not equipped with an active cushion, which is provided to provide on the vertical of the recording device 9 vnug When given borehole. However, pillow 14 may contain w-electrodes under additional means for studying the surrounding formations. Electronic signals containing information obtained by the recording device are transmitted via cable to the computing module 15 and the recording device 16 located on the surface of the earth. The oracle shown on phage 1 and designed to ensure that the antenna is in contact with the drill wall) is illustrative, and therefore it should be borne in mind that for this purpose it is possible to use (other means, for example hydraulic means). Figures 2 and 3 illustrate in a simplified form the nature of the propagation of an electromagnetic wave, whose parameters are measured by the device described in Fig. 1, Pillow 13 (Fig. 2) is located opposite the wall of the drills "L well 2, and the space between them is filled Flushing for drilling 17. In general, the pressure of a fluid in a formation intersected by a drill hole is less than the hydrostatic pressure of the solution column in the borehole, as a result of which the drilling fluid and its filtrate to some extent penetrate into the formation. The latter retain small particles that form a slurry in the drilling fluid, as a result of which a solid drilling mass is deposited on the borehole walls. Its thickness is between the parameters of the formation, for example, permeability, but there is always at least a very loose layer of solid drilling mass on the wall of the drill hole. As shown in FIG. 2, the pad 13 is in contact with a solid mass 17, shown for greater visibility on an enlarged scale. Transmitting antenna T emits microfiber electromagnetic energy into the formation under study (shown by arrow A). In order to characterize the motion of this wave in the direction of the npieM-NIKOV, consider FIG. 3, which shows the interface 18 between the lower loss region, the dielectric constant which is equal to & {, and the lossless upper region, the dielectric constant E is. It is known that the energy propagating from the source 5, which is an excited dipole, to the observation point O is the name of the surface wave, which consists of three main waves: direct, 1 reflected, and psherechnoy, as shown in FIG. 3, the Wheatwave wave forms the main part of the dngalo field and is dispersed near the interface, especially when the distance between points S and O is large compared to their cooler distances from the given interface. The transverse wave starts at the source in a medium with losses and propagates in the form of a beam to the interface in the direction which is determined by the critical angle, which is defined as follows: 5 This wave propagates along the boundary in the medium without loss. but it loses energy, scattering medium in the middle of aoger. The wave and reflected waves are limited by a lossy medium. The rate of decay of these signals is exponential, and it exceeds the algebraic speed from which the shear wave decays.

1) 1.O8

The principles of idiomatic manipulation, shown in FIG. 3, can be used for cases where the upper popupprogramgvo predsgavp a medium with low losses, which is right

provided that the dielectric constant of the upper half-space is less than the dielectric constant of the lower ps of the spacer. A necessary condition for the initiation of lost holes for the device shown in 4ig. 2, in the general case, is the use of a water-based drilling fluid. They have a relatively high conductivity, as a result of which the masses deposited from them should have a relatively high dielectric constant (due to the high water content), as well as a relatively high conductivity. Thus, a solid drilling mass can be considered as a lower half-space with large losses, and an adjacent formation as an upper psychospace with (with relatively low losses). As it is assumed that The angular angle {that is, the angle at which the energy of the transverse wave enters the formation) will be relatively small.

The transverse wave propagating in the formation is shown in FIG. 235

arrow B, and its progression - arrow C. A psssherechna wave continuously loses some of its energy lost in an environment with large losses, while individual quantities of its energy, which are connected to the location of receivers 5 and 6, are indicated respectively by arrows J and E. If we assume that the distances represented by arrows D and E are essentially equal to each other, then we can see that the difference between the distance corresponding to the path of energy passing to receiver 5 (path ABJ)) and the distance appropriate put 0 rohozhdeni energy, pos1upayuschey the receiver 6 (path A-B-C-E) is equal to the distance L predstavlennok strepk C, e.g. the distance between the indicated energy receivers. In conjunction with this, to study the area of foraia, located opposite the area between receivers 5 and 6, you can

0212

used receiver of different signals.

For simplicity, FIG. Figure 2 shows the leachable zone or penetration zone that surrounds a solid drilling mass in a borehole. As is known, the invaded zone contains fluids that penetrate from the drilling fluid, which is filtered through the solid mass of the drilling fluid and penetrates into the surrounding formations. The depth of such a zone of penetration generally varies from about 2.54 cm to several tens of centimeters, which depends on such factors as the connective properties of the drilling fluid and the lithology of the formations. If the depth of the penetration zone is relatively large, for example 30 cm or more, then the transverse wave generally passes through this zone in the same way as shown in FIG. 2, The dielectric constant defined by the recording device is thus the dielectric constant of the permeable formation, with the result that this information can be used in conjunction with other data to determine the parameters of the studied formation, such as porosity or lithology. If the depth of the penetration zone is relatively small, for example, of the order of 5 cm, then a significant transverse wave can form in a clean formation located beyond the penetration zone. This case is presented in a simplified form in FIG. 4. When using a water-based drilling fluid, the fluid contained in the penetration zone 19 causes a significantly higher conductivity of this zone and a higher dielectric constant compared with similar indicators for a clean formation. For this reason, the one shown in FIG. 4, the penetration zone 19 can be considered as a lower half-space with large losses, and the adjacent clean formation as an upper half-space with relatively low losses, which is similar to that shown in FIG. 3. In a similar way, a pseudo-wave can be formed in pure formia along the border with the invaded zone, as indicated by the arrow 20

In a pure formation dd case, shown in FIG.  4, to form a significant loss wave, the distance between T and 5 should be 13–1 greater than the depth of penetration.  There are practical limits to the maximum distance between a transmitter and receivers used in a device of this type.  In addition, if a significant transverse peak is formed in a pure formation, then a second transverse wave can be generated in the penetration zone along the boundary with the solid drilling mass, shown in FIG.  4 dotted arrow21.  The presence of two possible transverse waves is associated with the problem of presenting the results of the study.  Due to these reasons, in the preferred embodiment, the distance between the transmitter and the receiver is chosen relatively small, with ecm a significant transverse wave is generated only along the boundary of the formation, most closely spaced to the solid drilling mass, t. e.  within the zone of penetration.  FIG.  5 shows an electronic apparatus located in the housing of the supporting element 1, shown in the shaded area at the borehole wall.  The source-generator 8, {operating at a given frequency, generates at its output the energy of the microwave range 1 in the spectrum.  In this case, the microwave range includes frequencies located in the range of 300 MHz (t. e.  in the range of 300 MGy - 300, GTZ).  Generator B can operate at the required frequency on the order of 1.1 GHz, t. e.  with h1ast1 that 1,1 X ЮТц.  The selection of the required frequency of operation of the generator 8 is as follows.  Generator output 8.  through the decoupling device 22, the voe acts on the transmitting antenna T ,.  The new energy that comes from it is transmitted to the surrounding 1-D1F forms, in which it propagates in this manner.  The energy supplied to the receiving antenna 5 and b. accordingly, it is transmitted to the input terminals of the mixers 23, 24.  The signals from the receiving antennas 5 6 are shifted “about the phase relative to each other by an amount which is equal to the phase constant | 5, and the ratio of their amplitudes oni makes this attenuation constant about.  Microwave energy is applied to the second input terminals of these, the frequency of which is exposed from some 55 topd transmitters at a certain amount not very significant, used, for example, in the radio band.  In this 762 version, a generator with a fixed frequency of 25 delivers microwave inputs to the inputs of mixers 23 and 24 at a frequency of approximately 1.1001 GHz, or 100 kHz, at a higher frequency of the transmitter.  As a result, the output signals 23a and 24a of mixers 23 and 24. have a difference frequency of 1OO kHz.  In accordance with the known principles, signals 23a and 4a retain the phase and amplitude ratio of signals nociy-i transmitted from receiving devices 5 and 6, but the task of determining the phase is greatly simplified for signals with low frequency, in this case for shifted signals.  In order to ensure the difference between the operating frequencies of the generators 8 1 and 25, equal to 1OO kHz, and the output signals of these generators are fed into the mixer 26.  At the output of the latter there is a device for stabilizing the frequency 27 which detects a deviation from the predetermined frequency of 100 kHz and, in the presence of such a deviation, generates a correction signal 27a that controls the operation of the generator 25 according to the known method of locking the phase.  Signals 23a and 24a are detected by a phase detector 28 and an amplitude comparison device 29.  At the output of the phase detector 28, a signal is generated, the level of which is similar to the phase difference Φ between the signals.  perceived by receivers 5 and 6, therefore, is proportional to I, and therefore, proportional to - quality with the ratio P / L, - the distance between these receivers.  At the output of the device for comparing amplitudes 29, a signal is formed, the level of which is proportional to r, as shown in FIG.  6  Signals 23a. and 24a are amplified by corresponding logarithmics of the DA and 31, the outputs of which are transmitted to the input of the difference signal amplifier 32.  At the output of said amplifier 32, a signal is generated whose level is proportional to rpm; This can be seen if we imagine the amplitude perceived by receiver 5 in the form of Ae, where A is the amplitude constant, and 2 is the distance between the antenna antenna T and receiver 5.  It follows that the amplitude of the new energy perceived by receivers 6, ravdts-B1Sg: + b) - the distance between the indicated receivers 5 and 6 Ae 1 of the obtained expression follows that the logarithm of the wave amplitude amplitudes is proportional to (K,.  Thus, the device 29 shown in FIG.  6, performs the same functions and forms the required result when calibrating with the difference of the logarithms of the amplitudes of these signals.  The output signals of the phase detector 28 and amplitude comparison unit 29 (see  FIG.  5) transmitted upward through wires 28a and 29a. , being in the armored cable 10. Typically, these signals are transmitted in the form of continuous CCS levels that are amplified before transmission.  In the device located at the ground level, the signals transmitted by wires 28a and 29a affect the input of the computational module 15, which calculates the corrected solids taking into account the loss of the dielectric constant measured by the recording device located in the borehole,. in accordance with y (8) and / or (9) and (10).  The calculated value of the dielectric constant is recorded by a recording device 16 ,.  which works depending on the depth of the bursa well and is driven by the mechanical connection of the block balance - rotating Korefeca 33.  The wheel 33 is connected to the cable 10 and rotates synchronously with respect to the mixing of this cable, which ensures the operation of the recording device as a function of the depth of the borehole.  As a result, the dielectric constant values, corrected for the accounting loss, are recorded by means of the recorder 16 in accordance with the depth of the borehole.  FIG.  7 is shown. a circuit of a computational module 15, which receives signals transmitted via wires 28a and 29a, the information of which corresponds to the measured values and 0.  These signals first post to amplifiers with a variable gain factor 34 and 35, which can be used to perform the calibration.  Snails taken from the output of these amplifiers are fed to the corresponding inputs of known circuits for squaring 36 and 37, the outputs of which form signals proportional to the values of | 3 and оС.  The received signals are transmitted to the input of the difference signal amplifier 38, at the output of which a signal is generated, the value of which is proportional to the difference between the signals fed to its input, t. e.  differences 2 - 0 (7.  As follows from equation (8), the resulting output signal is a measurable value, since this equation can be rewritten as follows. Calibration of any parameters of the measuring device, such as frequency, can be performed using amplifiers 34 and 35. .  If necessary, the output signal of the differential difference amplifier 38 can be transmitted to the input of the circuit 3 9, extracting the square root.  The resulting output signal is the value of I, then according to equation (10). This signal can be recorded by recording device 16 in addition to or instead of the dielectric constant corrected for losses.  FIG. 8 shows a side view of the surface of the shoe, the cushion 13, which forms contact with the borehole wall.  Pillow 13 contains antennas T, 5 and 6.  It has been established that for transmitting and receiving transverse waves it is most efficient to use hollow antennas with a notch.  Shown in FIG. 8, the cavity openings are filled with a waterproof ceramic insulating material.  In this case, the cutout length is 7v | 2 IT “e.  about 7.5 cm for working.  1.1 GHz frequency (the dielectric constant of the insulating material is 4).  The distance D between antennas T and 5–8 cm, and the distance L between receiving antennas 4 cm.  The selection of the operating frequency and the corresponding dimensions are described below.  FIG.  9 is shown on an enlarged scale AA in FIG. 8.  In the meta-conductive conductive enclosure 40, there is a posit whose depth is D (4 tons). e.  about 3.75 cm  By means of the coaxial cable 1O, the antenna T is connected to the expansion device (isop brakes) 22 (Fig.  five).  The cable 10c will enclose the inner conductor 41 into the outer conductor sheath 42, which is usually filled with insulating material 43.  A probe 45 is located vertically inside the cavity 44, the central extension of conductor 41 continues. Usually, the adapter 45 enters at its end into a small cylindrical recess 46, located in the upper part of the housing, which is also filled with insulating material.  Receiving antennas 5 and 6 have the same design as the transmitting antenna, the design of which is shown in FIG. 8 and 9.  Through coaxial cable, receiving antennas are connected to mixers 23 and 24 shown in FIG.  five.  These three cables can be made in the form of a single cable with an armored sheath, which connects the shoe-block 13 with the device 1, which houses the submersible electronic equipment.  With regard to the choice of operating frequency and device sizing, it should be borne in mind that in accordance with equation (4) it is necessary to use a very high frequency () in order to reduce the value of the loss tangent.  For salt-containing rocks, saturated with water, for example, sandstone, is a loss of dielectric constant (meaning xAlelex value, considered ъ - more at frequencies below 100 MG Erk, larger frequencies decrease and in range, 6nH3K (Mvt to frequency 5OO MHz becomes larger as a result of which the measurement of magnitude becomes a simple task.  This is described, for example, in (1).  In the present case, it is described. The way in which the part of the supernational formation is used as a dielectric material, pacnonoHceHHoro between the plates of the capacitor, schich than.  Recorder electrodes are used as indicated plates.  However, such a method, as well as the schemes related to it, in accordance with which the kssle / eem formation should be used as a transmission line or caustic load, is not suitable for industrial use as a recording device. With an increase in the operating frequency in the gigahertz range Becoming Stanovits significantly,,.  Such a phenomenon predisposes the choice of high frequencies.  However, in practice it turns out that there are limits for choosing high values of operating frequencies.  One of the reasons for their SIA is an increase in magnitude / due to losses due to bipolar relaxation, which occurs when the frequency increases to values substantially exceeding 1 Wx.  Another reason is due to the influence of the hard drilling mass ha formation of a transverse wave in the formation at very high frequencies.  For the frequencies of the gigahertz range, the wavelength, with transient energy, is extraordinary ,.  but small, due to which the eye begins to penetrate into thicker layers of a solid drilling mass.  If this phenomenon takes place, then the solid, solid mass begins to play the role of a waveguide, along which a part of the transmitted energy is branched off.  As a result, the amount of energy to form a shear wave is reduced.  The indicated effect of the drilling mass begins to be seriously affected when half the wavelength of the transmitted energy into the drilling mass npi does not enter the thickness of the drilling mass.  For an approximate calculation, it should be assumed that the maximum thickness of the brown mass is about 2 cm, and the maximum dielectric constant of this mass is approximately 20.  This means that the maximum value for half of the wavelength I / 2 for free space, which satisfies the condition, is defined as follows: Ae / 2 (2 cm) {) 9 cm, or. d 18 cm, which corresponds to oks about 2 TTP, From the above reasoning it follows that the gattimal operating frequency range is located between the frequencies slightly higher than 500 MHz and slightly smaller than 2 GPa.  The frequency used in this embodiment is located within the specified range and is 1.1 GHz.  This frequency is satisfactory.  The choice of working device dimensions is dictated by practical considerations, some of which have already been considered.  As regards the distance D separating the antenna T o the antenna 5 (fng. 8), as it follows from the above reasoning with reference to FIG.  3 and 4, in establishing the predominant shear wave, it is desirable that the distance D be significantly greater than the thickness of the drilling mass.  However, if this distance to make an extremely large ego can lead to fading, making it difficult to carry out accurate measurements.  It has been established that a distance D equal to 8 cm (in general, four times the expected maximum thickness of the drilling mass) is satisfactory.  The choice of the specified distance must be made subject to specific conditions.  The distance L between the receiving angles must be sufficiently large to enable the determination of the required values for the different phases of the phases and to be relatively small so as to avoid possible ambiguous measurement.  The operating frequency of 1.1 GHz corresponds to a wavelength for a free space of about 27 cm.  The phase shift associated with the distance L between the receiving antennas from each other for free space is (11 Ff. space  At high frequencies, the phase shift is approximately proportional to the quadratic dependence of the dielectric constant 5d of the medium under study (see , for example, equality 3), due to which the total cooTHtMueHHe resulting from equation (11) has the form.  FM% ° 1K / / 3. ° 1fё; / H (l2 The smallest dielectric value of CONSTANT is usually about 4 in practice, which is the case for non-porous quartz rocks.  For such a dielectric constant value, the minimum phase shift at the distance it is determined as follows: PMHN. Fl. , (13) The largest dielectric constant occurs in limestone, which is fully saturated with water, whose porosity is about 35%.  The lag of the basics of microwave energy propagating in the composite formation is the volume-related sum of the lag in the pore fluid and the lag in the crystalline mass.  Thus i, the effective maximum value of the dielectric constant is determined from an approximate ratio; JT with: 0.35-4 + O, 65- eizvesr.  V with.  max1 - ,, water i ЛГВЗ + 0.65 From the above ratio is calculated with (in this case, fc- max.  about 30).  Thus, using equation (12), the maximum value of the phase shift for the length L can be determined as follows: F 13.3 (hG3).  (L) 73.21 / (14) from equations (13) and (14) it can be seen that the proposed separation length L 4 cm for this option is satisfactory.  voritelnsy.  With such a value of L, the minimum and maximum phase shifts are equal to about 106 and 293, respectively.  In the specified range, the phase shift can be determined with good resolution (in the range of more than 200) with ambiguity orcyv, which occurs in the presence of a range greater than 300.  In addition, a distance of 4 cm is not associated with the frequent problem of too much attenuation, with the result that such a distance is satisfactory.  In Dunn (I "1 case, the choice of the specified size can be made with some flexibility within the limits of permissible values and taking into account practical features.  By measuring the dielectric constant, the measurement of which is performed in accordance with the inventions, the required information regarding the porosity, the knowledge of the W of water saturation in the studied formation can be obtained.  If the dielectric constant of the incoming crystalline weighing and pore fluids are denoted by coorBeiv.  As in (and E go, taking into account the laid-out, you can fill in / - / -VE ;: p f 7 the de-porosity of the crystalline substance.  EslnS and.  determined from other logged information.  The value of porosity can be calculated by measuring the value of Q.  So, for example, if it is known that some formation consists of limestone (y, 7.5), by 1OO% saturated with water (b 8), the porosity can be of the following ratio; BWC (1 +) +Г + Г8о по1 If the porosity is pre-determined, the saturation values or the lithologists can be calculated by determining the dielectric CONSTANT composite formation.  Equation (15) can be rewritten as follows: This equation is used to calculate porosity using the circuit shown in FIG.  10, which can be considered as an additional part of the computing module (FIG.  5) The output signal of the square root extraction circuit 3 9 shown in FIG.  7, corresponds to Pj, the value of which, as can be seen from equation (9), is proportional to Q and r In those cases, the value of T is determined from the information ni received by the recording device or by taking a sample, voltage signals proportional to these values can be supplied to the appropriate input terminals of the difference signal amplifiers 47 and 48.  Output signals these difference signal amplifiers are respectively proportional to the numerator and denominator of the equation ().  These output signals are supplied by the HO input of the dividing circuit 49, which forms at its output a signal that is the porosity of the composite formation.  In the diagram of FIG.  11 shows a second embodiment of the device, which is intended to study the subsurface formations 4 intersected by borehole 2, Borehole 2 is usually filled with drilling fluid for drilling or drilling mass containing crushed solids in the form of a slurry.  The logging device 1 is immersed in the borehole 2 by means of armored cable 10, the length of which essentially corresponds to the relative depth of the device 9.  The cable dandruff is controlled by a corresponding cable located on the surface, for example, using a drum or a winch (not shown).  The logging device includes an elongated support element of a cylindrical mold, the inner part of which is made in the form of a waterproof case in which the electronic equipment is submerged in a borehole.  A pair of arc springs 11 and 12 is attached to the carrier element, 13 is fastened to the spring 11, inside of which are transmitting antennas T and T and T and two receiving antennas 5 and 6 separately separated from each other, the latter being distributed between transmitters essentially on the same axis with them.  A second pad 14, KOTOpasi, may be inactive to the spring 12 and serves to ensure an even vertical movement of the logging device 1 inside the borehole.  In the case of non-; However, electrodes and other additional means can be located in the cushion 14 for exploring surrounding formations.  Electronic signals containing information obtained by a logging device are transmitted via cable 10 to a computing module and a recording device (not shown) located on the surface of the earth.  Shown in FIG.  11, special means for keeping the antennas in contact with the wall of a drilling well are illustrative, and other means may be used, for example hydraulic means.  FIG.  12 in a simplified form, the Pdaazan character of the propagation of an electromagnetic wave, whose parameters are measured by the device shown in FIG.  eleven.  As shown in FIG.  12, the pad 13 is located opposite the wall of the borehole 2, which, as indicated, is affected by the drilling fluid for drilling.  Typically, the pressure of the fluid contained in - ohmaiah x, intersected by the borehole, is less than Sdr x; the tatic pressure of the column of drilling mass present in the borehole, as a result of which the drilling mass and its filter penetrate to a certain extent into the formations under investigation.  Aka; the formation 31O of the predgavl south is a screen for small particles suspended in the drilling fluid, as a result of which a solid drilling mass is formed on the walls of the drilling well.  Its thickness depends on the parameters of a specific formation, such as permeability, but in any case, at least a very thin layer of solid drilling mass is formed on the borehole wall.  As shown in FIG. 12, the pad 13 is in contact with a solid drilling mass 17 (shown on an increased scale).  The propagation of an electromagnetic wave starts from the transmitter T in the direction of arrow A, with a portion of the wave energy perceived by antennas 5 and 6, sTl one, the river wave propagating in pharmacy adjacent to the surface is divided between level 17 and formation 4 in the drawing is represented in the drawing by arrow B and its continuation is arrow C, the shear energy continuously scatters c in a solid drilling mass, while parts of the energy that are dissipated near the location of receivers 5 and 6 are represented by arrows J} and E, the other propagating from the waves and, as shown, begins at transmitter T2 along dotted arrow F and propagates as a shear wave in the direction shown by dotted arrow G.  Some of the energy of this wave propagates in the direction of the receiving antenna 6, and the other part in the direction of the receiving antenna 5, Due to geometric coincidence, the given wave from the antenna Tr passes a distance, the lengths of which correspond to the arrows E and C 4-D. The reasons for the use of waves whose propagation starts from antennas T are removed. At 11, the submerged electronic equipment, located inside element 3, is shown at the shaded area near the borehole wall. The output signals are energy with the frequency of the microwave range of the spectrum. In this case, the specified generator generates signals with a frequency of 1.1 TT, t. e.  with a frequency of 1.1 x 10 Ha.  The output of the generator B is connected via an isolating device 22 to an electronic switch 5O, two outputs of which are connected via coaxial wires soy 62 to the transmitting antennas T / and Tu.  The preferred type of antennas used in this case for transmitting and receiving antennas, the same as described in detail with reference to FIG. 8, t, e, in this case also hollow antennas with a cutout are used.  A control signal taken from one of the auxiliary outputs of the square pulse generator 51, operating at a frequency of 100 Hz, controls the operation of the electronic switch 50, the control square signal and its auxiliary signal are shifted relative to; each other at 180, are used to ensure synchronous operation. As a result, by using the control signal LT, the transmitters T and T alternately record for a time of 10 ms.  Receiving antennas 5 and 6, respectively, are connected by coaxial wires to data processing channels 52 and 53, each of which includes a mixer n amplifier, connected in series.  The signals arriving at the receiving antennas are phase-shifted relative to each other, and the magnitude of this shift depends on the value of the constant phase /, and the exclusion of their amplitudes is determined by the constant attenuation (,. In addition to the signals from receiving antennas 5 and 6, the corresponding inputs of each of the mixers 23 and 4 receive energy signals whose frequency differs from the transmitter frequency by a certain amount of the microwave band. In this case, a given frequency generator generates microwave energy signals the inputs of mixers 23 and 24, whose frequencies are equal to 1.1 OO1 GHz or 1OO kHz higher than the frequency of the transmitter, In accordance with known principles, the signals of mixers 23a and 24a keep the phase relation signal amplitudes received from the receiving antennas 5 and 6, but in this case greatly facilitated the task of determining a phase difference between said signals as OVDs are less chasg "the.  In order to provide a given difference in the frequency of sigval1da between the generators 18 and 25 SO kHz, the outputs of these generators are connected to the mixer 26.  The output signals of the mixer 26 enter the frequency stabilization circuit 27, which determines the frequency deviation from the value of 100 kHz and, if present, generates a correction signal 27a, which controls the operation of generator 2 according to the known method of locking the phase.  The output signals of mixers 23 and amplified by amplifiers 54 and 55, after which the output signals on two channels, designated 54a and 55a, are transmitted to the inputs of the functional nodes 56 and 57.  Signals 54a and 55a, respectively, are transmitted to the inputs of the detectors zero 56 and 57, the output signals of which are fed through wires designated 56a and 57a.  The wire 56 and is connected to one of the inputs of each of the Andic element 58 and 59.  The wire 57 is connected to one of the inputs of each logical element And 60 and 61.  The second inputs of the logic elements And 58 and 59 are affected by the signal controlling the generator 51, the second inputs of the logical elements 6O and 61 are influenced by the antiphase signal from the same generator.  The outputs of the logic elements 58 and 61 are connected together, with sig.  The currents generated at these outlets are used to flip the trigger 62 in the forward direction.  The outputs of logic elements 60 and 61 are also combined, and their output signals are used to flip trigger 62 in the opposite direction.  The output signal of the trigger 62 is sensed by the averaging or measuring circuit 63, the output signal level of which is a function of the average value of the phase difference of the signals 54a and 55a.  The operation of the functional unit 64 may be described using FIG.  13 j on the charts | and U of which the characteristics of the signals 54a and BBa are shown. Suppose that a part of the indication signal is a positive (or} effective inclusion) :, in re: what the transmission of the transmission-drive T is driven by.  In this case, the energy spread is initially perceived by the receiving antenna 5 and then 8.  In a response, signals 54a and 55aj are ultimately formed, with the signal 54a trans. At the 5th phase, the BB signal on the Qt I borehole as shown on flash 13, the B6 Detector and 57 form on their outputs, short peak pulses every time the signals on their inputs are reduced, the protective value decreases to zero cut forward to the specified reference level zero.  This target can also be applied to other tigal detectors, for example, those that determine the zero level crossing both with decreasing from positive values and with increasing from negative values.  On the graphs W and IV of FIG.  13 shows the output signals 56a and 57a.  If a single signal acts from the generator 51, there is no anti-phase signal, as a result of which the peak signals of the detectors can pass only through the logic elements 58 and 61.  The output of logic element 58 flips trigger 62 in the forward direction, while the output of logic element 60 flips trigger 62 in the opposite direction.  Accordingly, at the output of flip-flop 62, the signals shown in the graph Y are formed, which are a series of pulses B whose width corresponds to the phase angle S-i.  Measuring circuit 63 senses the indicated pulses and generates at its output a signal whose level corresponds to the area of a certain number of successively nociy pulses.  The height of the incoming pulses has a constant value, as a result of which the output level of the measuring circuit 63 corresponds to the phase angle Q The case when 10 ms has passed, after which the control signal changes polarity from the output of the generator 51.  In this case, the transmitter T „is activated, and the propagating microwave energy is initially sensed by antenna 6, and then 5.  In this case, the signal 55a is ahead of the signal 54a in phase by the amount of angle 0.  This leads to the fact that the peak signals 57a are ahead of the peak signals 56a by a time, the duration of which corresponds to the phase # 2. Since this remnant has a different control signal from the generator 51, the peak sigals of the detectors can be straightforward. 1MK elements 60 and 61, as a result of which the comparison of the phaeomas in the annals case is the opposite of the case considered.  the output of the signal of the logic element 61 moves the flip-flop 62 in the forward direction, while the output signal of the logic element 59 flips the flip-flop 62 in the opposite direction.  As a result, the trigger 62 generates pulse signals at its output, the width of which corresponds to the angle of & 2, and the output of the measuring circuit 63 produces a signal whose level reflects the value of the phase angle 02 In a preferred bHWvfT version, the time constants of the measuring circuit 63 are chosen as in such a way that their magnitude is sufficient to ensure the addition of the incoming pulse signals from the output of the trigger, resulting from the repeated sequential action of the signals from the generator 51.  Thus, the output of the integrator is a function of the averaged value of the phase difference, measured during the multiple cycles, t. e.  is the average magnitude of the phase angle Q and the Functional Node 64 is intended to measure the relative attenuation of bobbles entering channels 52 and 53.  Signals 54a and 55a affect, respectively, the inputs of logarithmic amplifiers 65 and 66, the output signals of which in turn affect the inputs of the detectors 67 and 68, respectively.  Pointed output signals from detectors 67a and 68a are transmitted via electronic switches 69 and 7O over external conductors to nicks 71 and 72.  The operation of the switches is controlled by antiphase signals from generator 51, with the result that their output signals are in turn received at output lines 71 and 72.  The synchronization in this case is such that the signal coming from a nearby receiver is always transmitted via line 71, and the signal coming from the far receiver is always transmitted via line 72.  Conductors 71 and 72 are connected to the input terminals of a differential amplifier 73, which forms a signal at its output, using the constant-attenuation function for a given formation o {,.  This can be easily noticed, if the amplitude of the wave energy, perceived by a close receiver, is represented as Ae, where A is the amplitude constant, and in Z the distance between the active gear and the nearest law.  It follows that the amplitude of the wave energy perceived by the far receiver can be represented as, where t is the distance between the indicated receivers.  Thus, the amplification of amplitudes can be made (no energy, perceived by these two receivers, can.  be written in the following way:. As sper from this equation, the logarithm of the ratio of the wave amplitudes is proportional to c6.  Functional node 64 performs the specified mathematical calculation by calculating the logar's performance (| mov of the specified wave amplitudes.  The switches 69 and 7O perform a sequential change in the reverse comparison of the amplitude values, as a result of which signals are sent to the inputs of the difference signal 73 amplifier with the corresponding COOTHD division of the amplifier. | The signal produced at the output of the difference signal amplifier 73 is transmitted to the averaging circuit 74, at the output of which a signal is generated whose level is a function of the average relative attenuation calculated for a plurality of cycles of the M or M signals.  When considering the operation of the device shown in FIG. 11 - it should be assumed that the elements of the receiving circuit operate in the prescribed mode.  In this case, the phase angles, t. e.  angles b and 8 are actually a function of the length of the signal path between the transmitter and the receivers (Fig.  12) and the phase constant ft, inherent in the Q1H of the considered paths of the passage of signals.  Thus, Q is a function of the distance traveled by the sipnal T1 10 - T1 9, which can be written using the notation of FIG.  12, to the following images: (A2B-Yu + E) (A + & 4-E) C + E -D.  Similarly, the phase angle Vg is a function of the T2-10-T2-9 path signal that can be written otherwise (r + Q + C- + L) (G + (+ E) C + and - E.)  Considering that the values of the phase angles B and 2 are averaged by the functional node 64, after the reduction of the terms of the tea, that the measured average phase value is a function of only C.  Since C is a constant dissection with itself, the measured mean is 29. 1O, the phase value is information about the phase constant in a continuous formation.  In that case, when E and JD are identical to each other, the phase angles q: and $ 2 are even.  Forced tires are the paths traveled by signals to the measurement ({by an initial draft, 64 zatuhani is essentially the same as that considered.  Suppose that one-way operating channels, for example 52, receive a signal with a very small erroneous phase shift B, which T-I c does not enter through the appropriate channel 53.  In such a signal, 54a has a small component of the O phase, which is not a function of the phonation under study.  The presence of the taxa component of the phase error does not violate the correct definition of the phase angle, since it is destroyed by averaging.  In particular, in the presence of a control signal from the generator 51, this error is + 5 and in the absence of this signal this error is - o, since the comparison is made in the opposite direction in this case.  The same correction takes place when the amplitude deviates from the result of the incoming through an additional or other channel.  62 The output signals corresponding to the measured values (b and o (, are transmitted via cable 10 to the earth's surface) and arrive at the input of the computational module and / or recording device or similar device for recording incoming information.  There should be some flexibility in choosing a device that senses the signals transmitted to the ground for further processing.  For example, signals transmitted over conductors 71 and 72 can be transmitted to the input of an amplifier of difference signals located on the surface of the earth.  However, most of the devices shown in FIG.  11 is preferably submersible in the well.  It should be borne in mind that various changes are possible that do not violate the meaning and are not beyond the scope of this invention. For example, the device shown in FIG.  11 may include preamplifiers for Channels 52 and 53, up to the mixers.  The described exclusion of possible small errors can be applied to any of the additional amplifiers, as well as to other elements of this device, for example, to the zero-signal detectors.

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Claims (4)

1. The method of electromagnetic logging, in which electromagnet energy is introduced into the surrounding formations to form a secondary wave in them, including measuring the propagation velocity of electromagnetic energy through a given part of the surrounding formations, the speed being an indicator of the parameters of the earth formations, characterized in that, for the purpose of increase measurement accuracy; dielectric constant of the studied formations, the electromagnetic field is excited in the region of microwave frequencies. 2. The method according to π. 1, it is obvious that the electromagnetic pope is excited in the frequency range 500 MHz - 2 GHz. 3. The method according to p, 2, excellent and h a torn and th s.i. that the electromagnetic field is excited at a frequency of 1.1 GHz ± + _0.1 GHz. 4. A device for implementing the method according to π. 1, comprising a support post installed in a borehole, means for introducing electromagnetic energy into surrounding formations located on the support post, a transmitting antenna, first and second receiving antennas installed in spatial communication with respect to means for introducing electromagnetic energy and at a predetermined distance with respect to to the surrounding formation, while the means of introducing electromagnetic energy are connected to the receiving antennas, and a device for measuring the propagation velocity of electromagnetic energy through this part of the surrounding formations is indicative of the earth formation parameters, characterized in that the means for introducing electromagnetic 'hydrochloric energy comprises a source of microwave frequencies.